Thin film transistor liquid crystal display (TFT LCD) has already become a crucial display platform of modern IT and video products. The main operating principle of the TFT LCD: appropriate voltage is applied between the liquid crystal layers of an array glass substrate and a color filter (CF) glass substrate, so that liquid crystal molecules are deflected under the action of the voltage, and different penetration rates are obtained by the control of different voltages. Thus, display is achieved. Because an LCD can not emit light by itself, a backlight source is used as a source of the light source of the LCD. The LCD backlight source at present mainly includes a (cold cathode fluorescent lamp) CCFL backlight source and a light-emitting diode (LED) backlight source in accordance with different light emitting devices. The LED backlight source is welcomed by consumers because the LED backlight source is superior to the CCFL backlight source in the aspects such as volume, color range, efficiency and the like.
FIG. 1 is a section diagram of a backlight module with an edge type LED backlight source. The backlight module includes an LCD panel 1, an optical diaphragm 2, a light guide plate (LGP), a reflection sheet 4, a backplane 5, an LED light bar 6, a radiator 7, a front frame 8, screw(s) 9 and the like.
The positioning modes of the LGP are different in accordance with different size and requirements. FIG. 2 shows a positioning mode of an LCP 3 of one size, the LGP 3 is provided with five positioning points in total, namely the positioning holes 32 shown in the figure. The five positioning holes 32 are respectively a, b, c, d, and e. The stress directions of the positioning holes 32 are shown as the arrow directions in the figure. The number (pressure) and size of the stress points of the LGP 3 are different when the LCP 3 is in different vibration directions. When the LGP 3 is in the horizontal vibration direction, the stress points may be a, b, and c or the combination of a, b, and c. FIG. 3 is a simplified structure diagram of the positioning hole 32 (a) matched with a rivet 31 on a backplane 5. The rivet 31 is inserted in the positioning hole 32, so that the LGP 3 is limited in three directions. In accordance with stress analysis, as shown in FIG. 4, obvious stress concentration is produced at the root of the positioning hole 32 (a) because of undersize R1 and R2 angles, easily causing the LGP 3 to rupture.